The invention relates to an arrangement for clamping workpieces in machine tools, particularly for clamping crankshafts in grinding machines or lathes, which is journalled in a spindle stock or secured to an indexing head and is provided with a workpiece support and with pivotable clamping means for receiving and clamping a workpiece, or the terminal crankpin.
Such an arrangement is already known from DE-AS No. 21 10 469. It is journalled in a spindle stock. To receive and clamp the workpiece the arrangement has a workpiece support and a clamping arm which is pivotable by a hydraulic piston and holds the workpiece by engaging the workpiece, the terminal crankpin, opposite the workpiece support by a clamping jaw provided with a planer clamping surface. Since the arrangement is primarily intended for crankshaft grinding machines, both terminal crank pins are clamped in one arrangement each.
It must be considered a disadvantage of the known arrangement that, to operate the hydraulic piston, a substantial amount of hydraulic and electrical control equipment is required and that the one clamping jaw which clamps the workpiece has a planar clamping surface and is not subject to any predetermined initial stress. Due to the small contact surface between the workpiece and the jaw, the situation recurs that a workpiece, which must be clamped in a specific position, turns during machining. Since all operating elements are freely accessible, it is necessary to carry out constant maintenance work.